Many customers will ask PCB manufacturers to make Halogen Free PCB Board. Halogen Free PCB Board is an environmentally friendly material, and the substrate used for Halogen Free circuit board is processed with Halogen Free raw materials.

Electronic devices contain certain materials that contain the highest concentrations of halogens. In order to create a Halogen Free circuit board in electronic equipment printed boards, it is necessary to replace certain materials or reduce their use on the board. It is also necessary to determine the halogen-free content of the circuit. Some alternative substances require special design considerations, which ultimately need to be considered as well.

At present, the vast majority of halogen-free sheets are mainly phosphorus-based and phosphorus-nitrogen-based. When the phosphorus-containing resin is burned, it is thermally decomposed to generate metaphosphoric acid, which has strong dehydration, and forms a carbonized film on the surface of the polymer resin, which isolates the burning surface of the resin from contact with the air, so that the fire is extinguished and the flame retardant effect is achieved. The polymer resin containing phosphorus and nitrogen compounds produces non-combustible gas when burning, which helps the resin system to flame retardant. So, what are the characteristics of halogen-free sheet?

1. Insulation of materials

Due to the use of P or N to replace the halogen atoms, the polarity of the molecular bond segment of the epoxy resin is reduced to a certain extent, thereby improving the insulation resistance and breakdown resistance.

2. Water absorption of the material

The halogen-free sheet has less N and P pairs of electrons than halogens in the nitrogen-phosphorus-based redox resin, and the probability of forming hydrogen bonds with hydrogen atoms in water is lower than that of halogen materials, so the water absorption of the material is lower than that of conventional halogens. Department of flame retardant materials. For the sheet, low water absorption has a certain influence on improving the reliability and stability of the material.

3. Thermal stability of the material

The content of nitrogen and phosphorus in the halogen-free sheet is greater than that of ordinary halogen-based materials, so its monomer molecular weight and Tg value are increased. In the case of heating, its molecular mobility will be lower than that of conventional epoxy resins, so the thermal expansion coefficient of halogen-free materials is relatively small.

Growing demand for Halogen Free PCBs

Compared with halogen-containing sheets, halogen-free sheets have more advantages, and it is also a general trend to replace halogen-containing sheets with halogen-free sheets. At present, there are many kinds of halogen-free solder resist inks on the market, and their performance is not much different from that of ordinary liquid photosensitive ink, and the specific operation is basically similar to that of ordinary ink.

Halogen-free circuit boards usually have good heat dissipation reliability and are more suitable for high-temperature processes required by lead-free circuits. It also maintains signal integrity due to its low dielectric constant. So the demand for Halogen Free PCB has been increasing.